• Title/Summary/Keyword: 에너지경사

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Estimation of Absorbing Capacity from Rockfall Protection Fences (도로 낙석방지울타리의 낙석지지능력 평가 연구)

  • Hwang, Young-Cheol
    • Journal of the Korean GEO-environmental Society
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    • v.3 no.4
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    • pp.59-66
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    • 2002
  • Designs for rockfall protection systems must consider rock and soil types, the angle of the slope, conditions on top and the toe of the affected area. Rockfall protection fence is installed to block for falling rock from cut slopes and this is one of the most common rockfall protection measures. The capability of the fence is provided that sum of capability of poly vinyl chloride coated wire mesh, steel support and wire rope respectively. But in some case, the rockfall protection fence was not supported rockfall energy less than total capability of the fence through the full scale rockfall tests. Therefore, the objectives of this paper are to indicate the problems of fence capability and to improve the design specifications for the fence.

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Performance Characteristic Analysis of Small Hydropower for Buddhist Temple (사찰의 소수력발전 성능특성 분석)

  • Park, Wansoon;Lee, Chulhyung
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.208.1-208.1
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    • 2011
  • 우리나라 전국의 사찰수는 약 22,000개로 추정되며, e-나라지표에 의하면 사찰 역사가 오래되거나 전통 양식의 건축물과 문화재 등을 간직한 사찰로 문화체육관광부가 지정하는 전통사찰은 2010년 3월말 현재 전체의 4.2%인 935개로 알려져 있다. 대도시에 위치한 사찰을 제외하면 일반적으로 사찰은 계곡에 위치하여 인근에 하천이 있으며, 유역이 작아 유량은 적으나 경사가 심해 낙차를 크게 얻을 수 있다. 또한 설계제원이 비슷한 전통사찰들을 그룹핑하고 소수력발전시스템을 Kit형태로 표준화하여 개발한다면 초기투자비를 저감할 수 있는 장점도 있다. 따라서 본 연구에서는 전통사찰에 소수력발전의 적용가능성을 타진하기 위하여 유역면적이 $49.71km^2$인 사찰 1지점을 선정하여 인근의 하천을 이용한 소수력발전 성능특성을 분석하였다. 분석결과 단위 유효낙차당 설비용량은 약 9.3kW, 연간전기생산량은 약 28,602kWh로 산정되었으며, 낙차가 커질수록 설비규모와 연간전기생산량은 비례하여 증가될 것으로 추정된다. 부존자원이 부족하여 에너지해외의존도가 97%가 넘는 현실을 감안할때 전통사찰에 대한 타당성 조사를 통해 소수력발전을 적용함으로서 사찰에서 사용되는 전기에너지의 절약과 친환경 재생에너지의 활용을 확대해 나가는 것이 바람직 할 것으로 사료된다.

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Wave Transformation Due to Energy Dissipation Region (에너지 감쇠영역으로 인한 파랑변형)

  • 윤종태
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.11 no.3
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    • pp.135-140
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    • 1999
  • To simulate the wave transformation by an energy dissipation region, a numerical model is suggested by discretizing the elliptic mild-slope equation. Generalized conjugate gradient method is used as solution algorithm to apply parabolic approximation to open boundary condition. To demonstrate the applicabil-ity of the numerical procedure suggested, the wave scattering by a circular damping region is examined. The feature of reflection in front of the damping region is captured clearly by the numerical solution. The effect of the size of dissipation coefficient is examined for a rectangular damping region. The recovery of wave height by diffraction occurs very slowly with distance behind the damping region.

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Experimental Study for Wave Energy Convertor using Floating Light Buoy (등부표를 이용한 파력발전에 관한 실험적 연구)

  • Oh, Nam Sun;Jeong, Shin Taek;Ko, Dong Hui
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.1
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    • pp.50-55
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    • 2015
  • In this paper, wave energy convertors which convert incident wave energy into electric power using floating light buoy are investigated. One-tenth models of a floating light buoy, straight line and seesaw type electric power plant are manufactured and tested in wave flume. In these systems, we measure the horizontal and vertical slope, generated current and power of buoy with different wave heights and periods. This was confirmed the capability of getting electric power, then we suggest further works to get more efficiency.

Refraction angle of the transverse wave near the longitudinal critical angle in angle beam transducer (종파 임계각 근처에서 사각 탐촉자의 횡파굴절각)

  • Lee Jeong-Ki;Lim Seong-Jin
    • Proceedings of the Acoustical Society of Korea Conference
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    • autumn
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    • pp.303-306
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    • 2000
  • 복잡한 형상을 지닌 터빈 블래이드의 결함을 검사하기 위해 현재 $35^\circ,\; 38^\circ,\; 40^\circ$의 횡파 굴절각을 지닌 탐촉자를 사용하고 있다. 이와 같은 굴절각은 초음파 빔의 경로를 Snell의 법칙에 의해 설정하고 있다. 그러나 터빈 블래이드 검사용 초음파 탐촉자를 제작하는 과정에서 $35^\circ$의 횡파 굴절각을 갖는 경사각 탐촉자는 제작이 어려움을 알았다. 이러한 원인은 철강재료의 종파임계각이 $33.2^\circ$의 횡과굴절각에 대응되며, 종파임계각 근처에서는 전반사 현상 때문에 에너지 투과율이 매우 작아 실제 시험대상체에 입사되는 에너지가 거의 없으며 또한 횡파굴절각이 약 $37.5^\circ$ 일때에 휭파의 에너지 투과율이 최대가 되어 wedge를 $37.5^\circ$ 이하의 횡파굴절각을 갖도록 설계하더라도 측정을 하면 $37.5^\circ$ 근처의 횡파굴 절각을 갖게된다. 즉, 종파임계각 근처에서는 전반사 현상에 의해 경계면에서의 에너지 투과가 매우 작아 횡파 굴절각은 Snell의 법칙이 아닌 초음파 에너지의 투과 정도를 나타내는 echo transmittance의 크기에 의해 결정된다.

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Linear Shallow Water Equations for Waves with Damping (파랑 에너지 감쇠가 있는 경우의 선형천수방정식)

  • Jung, Tae-Hwa;Lee, Chang-Hoon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.24 no.1
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    • pp.10-15
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    • 2012
  • Wave characteristics in the presence of energy damping are investigated using the linear shallow water equations. To get the phase and energy velocities, geometric optics approach is used and then these values are validated through numerical experiments. Energy damping affects wave height, phase and energy velocities which result in wave transformation. When the complex wavenumber is used by the Eulerian approach, it is found that the phase velocity decreases as the damping increases while the energy velocity increases showing higher values than the phase velocity. When the complex angular frequency is used by the Lagrangian approach, the energy-damping wave group is found to propagate in the energy velocity. The energy velocity is found to affect shoaling and refraction coefficient which is verified through numerical experiments for waves on a plane slope.

Study on Combined Use of Inclination and Acceleration for Displacement Estimation of a Wind Turbine Structure (경사 및 가속도 계측자료 융합을 통한 풍력 터빈의 변위 추정)

  • Park, Jong-Woong;Sim, Sung-Han;Jung, Byung-Jin;Yi, Jin-Hak
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.35 no.1
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    • pp.1-8
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    • 2015
  • Wind power systems have gained much attention due to the relatively high reliability, good infrastructures and cost competitiveness to the fossil fuels. Advances have been made to increase the power efficiency of wind turbines while less attention has been focused on structural integrity assessment of structural sub-systems such as towers and foundations. Among many parameters for integrity assessment, the most perceptive parameter may be the induced horizontal displacement at the hub height although it is very difficult to measure particularly in large-scale and high-rise wind turbine structures. This study proposes an indirect displacement estimation scheme based on the combined use of inclinometers and accelerometers for more convenient and cost-effective measurements. To this end, (1) the formulation for data fusion of inclination and acceleration responses was presented and (2) the proposed method was numerically validated on an NREL 5 MW wind turbine model. The numerical analysis was carried out to investigate the performance of the propose method according to the number of sensors, the resolution and the available sampling rate of the inclinometers to be used.

Identification of vulnerable region susceptible to soil losses by using the relationship between local slope and drainage area in Choyang creek basin, Yanbian China (중국 연변 조양하 유역의 국부경사와 배수면적의 관계를 이용한 토사유실 우심지역 추출)

  • Kim, Joo-Cheol;Cui, Feng Xue;Jung, Kwan Sue
    • Journal of Korea Water Resources Association
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    • v.51 no.3
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    • pp.235-246
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    • 2018
  • The main purpose of this study is to suggest a methodology for identifying vulnerable region in Choyang creek basin susceptible to soil losses based on runoff aggregation structure and energy expenditure pattern of natural river basin within the framework of power law distribution. To this end geomorphologic factors of every point in the basin of interest are extracted by using GIS, which define tractive force and stream power as well as drainage area, and then their complementary cumulative distributions are graphically analyzed through fitting them to power law distribution to identify the sensitive points within the basin susceptible to soil losses with respect to scaling regimes of tractive force and stream power. It is observed that the range of vulnerable region by scaling regime of tractive force is much narrower than by scaling regime of stream power. This result seems to be due to the tractive force is a kind of scale dependent factor which does not follow power law distribution and does not adequately reflect energy expenditure pattern of river basins. Therefore, stream power is preferred to be a more reasonable factor for the evaluation of soil losses. The methodology proposed in this study can be validated by visualizing the path of soil losses, which is generated from hill-slope process characterized by local slope, to the valley through fluvial process characterized by drainage area as well as local slope.

Instability of Plunging Breaking Wave Impact on Inclined Cylinder (경사진 실린더에 작용하는 플런징 쇄파 충격력의 불안정성 고찰)

  • Hong, Key-Yong;Shin, Seung-Ho
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.10 no.4
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    • pp.187-192
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    • 2007
  • Impact on cylindrical surface caused by plunging breaking waves is investigated experimentally. The breaking waves are generated in a wave flume by decreasing the wave maker frequencies linearly and focusing the generated wave components at one specific location. The breaking wave packets are based on constant wave steepness spectrum. Three inclination angles of cylinder are applied to examine the effect of contact angle between cylinder and front surface of breaking waves. Also, the effect of cylinder diameter on pressure distribution and its peak value is investigated by adopting three cylinders with different diameters. The longitudinal location of cylinder is slightly moved in eight different points to find out a probable maximum value of impact pressure. The pressures and total force on cylinder surface are measured by piezo-electric pressure sensors and 3-components load cell with 30kHz sampling rate. The variation of peak impact pressures and forces is analyzed in terms of cylinder diameter, inclination angle and location. Also, the pressure distribution on cylindrical surface is examined. The cylinder location and surface position are more important parameters that govern the magnitude and shape of peak pressures, while the cylinder diameter and inclined angle are relatively insignificant. In a certain conditions, the impact phenomenon becomes very unstable which results in a large variation of measured valves in repeated runs.

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Implementation of Segway Using Pressure Sensors (압력센서를 이용한 세그웨이 개발)

  • Jo, Sung-Chan;Kang, Su-Min;Huh, Kyung-Moo;Joo, Young-Bok
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.1
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    • pp.285-290
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    • 2013
  • As well as the advanced development of modern society, and the environmental problems caused by the use of fossil fuels is emerging. So do not reap the performance level of the car to be able to replace existing fossil fuel and low-emission energy and technology development are continually strives. Therefore, this study aims to present the direction of the new interface 21st century Mobile Auto Electric Segway technology in the field of security and disadvantages based. The Segway is a problem because the control itself skewed by certain slope where the slope in the wrong adjustment tipping. In this study, the year saw the introduction of two pressure sensors(Load cell) used to solve these drawbacks, according to the ratio of the weight control methods. In addition, the ramps operate in a straightforward, using an acceleration sensor and a gyro sensor in order to compensate for the slope value in free control method to study looked. Measured by calculating the value of the occupant's weight and according to the inclination of the pressure sensor pressure sensing experiment results this year, we can see that the control variable for the change in body weight is greater than the inclination. Segway is also easy to control, and the stability of the ramps, etc. As a result, created using a pressure sensor.